Pulsed field electrophoresis as practiced today for separations of high molecular weight biomolecules such as DNA is allow electric field technique. Flat slab gels are employed, with fields typically in the range of 10 volts per centimeter or less, with corresponding electric field amplitudes of 10 volts per centimeter or less. Separations require times ranging from hours to days.
Workers in the area of pulsed field electrophoretic separations of high molecular weight biomolecules such as DNA have determined experimentally that electric fields higher than about 10 volts per centimeter of the gel used for the electrophoresis degrade resolution, relative to the resolutions attainable employing pulsed fields of 10 volts per centimeter or less.
It has been postulated that this is caused by elongation of the molecules in strong fields, and alignment of the molecules with such fields, with the result that the molecules traverse the gel more or less "end-on" in a process called "reptaton." When the separating molecules are in this stretched out orientation, they presumably interact with pores of a given size in approximately the same manner regardless of their lengths, and so long as the molecular charge and the friction on the molecules are proportional to the molecular size, as is the case for DNA, the molecules tend to traverse the gel under given conditions at approximately the same velocities, resulting in poor separations. It has been expressly recognized in the literature, however, that the factors affecting resolution in these systems are not fully understood at present.
An electrophoretic technique which overcomes the deficiencies of pulsed field electrophoresis as presently practiced and provides good resolution of high molecular weight biomolecules such as DNA in relatively short separation times would be very useful in medical and biological/biochemical research and testing. Such a technique is the subject of the present invention.